Questions regarding 11-036r2 (Transmitter training)

[Karthikeyan, Kishore K]

Formatted message: <a href="http://www.t10.org/cgi-bin/ac.pl?t=r&f=r1105022_f.htm">HTML-formatted message</a>

Thanks George for the clarifications.
Regarding #1:
I assume that your motivation to make differential high in the invalid marker
definition to be "greater than 25" is to account for the scrambled dwords
preceding the marker that can contain up to 3 ones. I agree with it.
Regarding #4:
I did not understand what you meant by the name of the bit not being correct.
Can you please clarify. The definition of TX_FIXED bit	did make sense to me
and it simply says that "my transmitter cannot be trained and so please don't
attempt to train it". And my understanding was that the TRAIN_COMP bit is 
used to indicate the training complete condition. So I did not understand why
we would want to change the definition of TX_FIXED to indicate "training
complete" event as TRAIN_COMP bit already serves that purpose.
Thanks
Kishore
From: Penokie, George [mailto:George.Penokie at lsi.com]
Sent: Monday, May 02, 2011 2:35 PM
To: Karthikeyan, Kishore K; t10 at t10.org
Subject: RE: Questions regarding 11-036r2 (Transmitter training)
Kishore,
Here's my response to your comments:
#1
Invalid does need to be defined as is invalid Dword is for DWS. I suggest the
following wording:
During the Train_Tx-SNW if the phy's receiver detects:
a)	a differential high signal level for at least 11 UIs but less than 19
UIs;
b)     a differential high signal level for greater than 25 UIs;
c)	a differential low signal level for at least 11 UIs but less than 19
UIs; or
d)     a differential low signal level for greater than 21 UIs,
then the pattern marker shall be invalid.
#2
There was much description in the Tx_Train-SNW as there currently is in the
Train-SNW in SPL. All the description is handled in SNW-3 in the definition
of the capabilities bits.
#3
That will be covered in the some to be written section on Manchester encoding
#4
The name of this bit is the largest problem and some added function that was
inadvertently added to the bit in the current published revision. The next
revision, out soon, renames the bit and redefines it back to its correct
function. That is to indicate when the both the local and attached phys have
completed the initialization sequence.
#5
Agreed- item a) has been completely removed.
#6
This was addressed in 11-044r0 on page 5. We will not be dword synced when
finished with Train_Tx-SNW. We are training our receiver during Train_TX-SNW
but the entire process will not be complete. The intent is not to keep
receiver coefficients constant during Train_TX-SNW.
#7
Fixed
#8
That line has been deleted in revision 3.
Bye for now,
George Penokie
LSI Corporation
3033 41st St. NW
Suite 100
Rochester, MN 55901
507-328-9017
george.penokie at lsi.com
From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of Karthikeyan,
Kishore K
Sent: Wednesday, April 27, 2011 8:47 PM
To: t10 at t10.org
Cc: Karthikeyan, Kishore K
Subject: Questions regarding 11-036r2 (Transmitter training)
Hi all
I was reading the 11-036r2 version of the transmitter training proposal and
had the following questions/clarifications.
Issue #1:
Section 5.7.4.2.3.4.2 Pattern marker  of the proposal defines what a "valid
pattern marker" message is. But there is no section that defines what an
"invalid pattern marker" message is. This definition is required because the
PTT_PL state machine uses both valid and invalid messages to make its state
transitions. If it is not defined, then depending on implementation an
"invalid pattern marker" message can be generated even during the 58 dwords
of scrambled and 8b/10b encoded data of the Tx training pattern.
I took an initial stab at the definition of "invalid pattern marker" as
follows.
During the Train_Tx-SNW if the phys receiver detects:
1.     A differential high signal level for greater than 10 but less than 19
UIs or
2.     A differential low signal level for greater than 10 but less than 19
UIs or
3.     A differential high signal for greater than 21 UIs or
4.     A differential low signal for greater than 21 UIs.
Then the pattern marker shall be invalid.
Issue #2:
The proposal does not say whether SSC can be enabled/disabled during Tx
Train-SNW. For all other windows the standard clearly mentions if SSC can be
enabled. The SP28SAS_TrainSetup state has a statement that implies that SSC
can be enabled in Tx_Train-SNW but it would be helpful to call it out
explicitly
Issue #3:
Proposal doesn't define the action that needs to be taken for invalid
Manchester Encoding received during Transmitter training information unit.
Meaning if the Manchester decoding does not result in either 1 or 0, what do
we do?
Issue #4:
In PTT_T1:Initialize state, why are we setting the TX_FIXED bit to one? Why
is it not defaulted to zero? If the local phy's pattern lock s/m does not
lock and hence the local phy don't receive any Transmitter Training
Information unit, it will continue to transmit this initial pattern with
(TX_FIXED = 1), but since the attached phy's pattern lock s/m got locked, it
will transition to PTT_T2:Tx_Training state and think that my transmitter
does not support Tx_Training (TX_FIXED = 1).  Am I reading this wrong?
Issue #5:
In PTT_T2: Tx_Training state, in page 58, the condition for setting
TRAIN_COMP bit seems to be a deadlock condition. Won't	points a) and b)
cause a deadlock? Basically why should we have to wait for local phy's
transmitter training complete message to set the training complete bit?
Setting the TRAIN_COMP bit should only depend on receiving a TX_FIXED = 1
|from the attached phy or Attached Phy's Transmitter optimized message
received.
Issue #6:
This question might be dumb but since I am not a phy expert, please bear with
me.
When we are doing Tx_Training, aren't we essentially training our receivers
too? Then why did we design the proposal such that if Train_Tx-SNW was
successful, we have to follow it with a Train_Rx-SNW? Is the intent to keep
our receiver coefficients constant during Train_Tx-SNW and only Train the
attached phy's TX coefficients and then modify the local phy's Rx
coefficients during Train_RX-SNW?
Issue #7:
Page 8, note k:
I think it should read --> (eg MTXT) is nominally 500.5 ms equals MTTT+RCDT
Issue #8:
Page 57, line 1.
I think it should read --> c) six or more Train_Tx Pattern Transmitted
messages.
Thanks in advance.
Kishore